/*
 * Based on arch/arm/kernel/signal.c
 *
 * Copyright (C) 1995-2009 Russell King
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <seminix/signal.h>
#include <seminix/linkage.h>
#include <seminix/syscall.h>
#include <seminix/tcb.h>
#include <seminix/init.h>
#include <asm/ptrace.h>
#include <asm/traps.h>
#include <asm/daifflags.h>
#include <asm/processor.h>

/*
 * Do a signal return; undo the signal stack. These are aligned to 128-bit.
 */
struct rt_sigframe {
    siginfo_t   info;
    ucontext_t  uc;
};

struct frame_record {
    u64 fp;
    u64 lr;
};

struct rt_sigframe_user_layout {
    struct rt_sigframe __user *sigframe;
    struct frame_record __user *next_frame;

    unsigned long size;	/* size of allocated sigframe data */
    unsigned long limit;	/* largest allowed size */

    unsigned long fpsimd_offset;
    unsigned long esr_offset;
    unsigned long sve_offset;
    unsigned long extra_offset;
    unsigned long end_offset;
};

#define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
#define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
#define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)

static void init_user_layout(struct rt_sigframe_user_layout *user)
{
    const size_t reserved_size =
        sizeof(user->sigframe->uc.uc_mcontext.__reserved);

    memset(user, 0, sizeof(*user));
    user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);

    user->limit = user->size + reserved_size;

    user->limit -= TERMINATOR_SIZE;
    user->limit -= EXTRA_CONTEXT_SIZE;
    /* Reserve space for extension and terminator ^ */
}

static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
{
    return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
}

/*
 * Sanity limit on the approximate maximum size of signal frame we'll
 * try to generate.  Stack alignment padding and the frame record are
 * not taken into account.  This limit is not a guarantee and is
 * NOT ABI.
 */
#define SIGFRAME_MAXSZ SZ_64K

static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
                unsigned long *offset, size_t size, bool extend)
{
    size_t padded_size = round_up(size, 16);

    if (padded_size > user->limit - user->size &&
        !user->extra_offset &&
        extend) {
        int ret;

        user->limit += EXTRA_CONTEXT_SIZE;
        ret = __sigframe_alloc(user, &user->extra_offset,
                       sizeof(struct extra_context), false);
        if (ret) {
            user->limit -= EXTRA_CONTEXT_SIZE;
            return ret;
        }

        /* Reserve space for the __reserved[] terminator */
        user->size += TERMINATOR_SIZE;

        /*
         * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
         * the terminator:
         */
        user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
    }

    /* Still not enough space?  Bad luck! */
    if (padded_size > user->limit - user->size)
        return -ENOMEM;

    *offset = user->size;
    user->size += padded_size;

    return 0;
}

/*
 * Allocate space for an optional record of <size> bytes in the user
 * signal frame.  The offset from the signal frame base address to the
 * allocated block is assigned to *offset.
 */
static int sigframe_alloc(struct rt_sigframe_user_layout *user,
              unsigned long *offset, size_t size)
{
    return __sigframe_alloc(user, offset, size, true);
}

/* Allocate the null terminator record and prevent further allocations */
static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
{
    int ret;

    /* Un-reserve the space reserved for the terminator: */
    user->limit += TERMINATOR_SIZE;

    ret = sigframe_alloc(user, &user->end_offset,
                 sizeof(struct _aarch64_ctx));
    if (ret)
        return ret;

    /* Prevent further allocation: */
    user->limit = user->size;
    return 0;
}

static void __user *apply_user_offset(
    struct rt_sigframe_user_layout const *user, unsigned long offset)
{
    char __user *base = (char __user *)user->sigframe;

    return base + offset;
}

static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
{
    struct user_fpsimd_state const *fpsimd =
        &current->thread.uw.fpsimd_state;
    int err;

    /* copy the FP and status/control registers */
    err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
    __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
    __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);

    /* copy the magic/size information */
    __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
    __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);

    return err ? -EFAULT : 0;
}

static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
{
    struct user_fpsimd_state fpsimd;
    __u32 magic, size;
    int err = 0;

    /* check the magic/size information */
    __get_user_error(magic, &ctx->head.magic, err);
    __get_user_error(size, &ctx->head.size, err);
    if (err)
        return -EFAULT;
    if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
        return -EINVAL;

    /* copy the FP and status/control registers */
    err = __copy_from_user(fpsimd.vregs, ctx->vregs,
                   sizeof(fpsimd.vregs));
    __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
    __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);

    clear_thread_flag(TIF_SVE);

    /* load the hardware registers from the fpsimd_state structure */
    if (!err)
        fpsimd_update_current_state(&fpsimd);

    return err ? -EFAULT : 0;
}

struct user_ctxs {
    struct fpsimd_context __user *fpsimd;
    struct sve_context __user *sve;
};

#ifdef CONFIG_ARM64_SVE

static int preserve_sve_context(struct sve_context __user *ctx)
{
    int err = 0;
    u16 reserved[ARRAY_SIZE(ctx->__reserved)];
    unsigned int vl = current->thread.sve_vl;
    unsigned int vq = 0;

    if (test_thread_flag(TIF_SVE))
        vq = sve_vq_from_vl(vl);

    memset(reserved, 0, sizeof(reserved));

    __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
    __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
             &ctx->head.size, err);
    __put_user_error(vl, &ctx->vl, err);
    BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
    err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));

    if (vq) {
        /*
         * This assumes that the SVE state has already been saved to
         * the task struct by calling preserve_fpsimd_context().
         */
        err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
                      current->thread.sve_state,
                      SVE_SIG_REGS_SIZE(vq));
    }

    return err ? -EFAULT : 0;
}

static int restore_sve_fpsimd_context(struct user_ctxs *user)
{
    int err;
    unsigned int vq;
    struct user_fpsimd_state fpsimd;
    struct sve_context sve;

    if (__copy_from_user(&sve, user->sve, sizeof(sve)))
        return -EFAULT;

    if (sve.vl != current->thread.sve_vl)
        return -EINVAL;

    if (sve.head.size <= sizeof(*user->sve)) {
        clear_thread_flag(TIF_SVE);
        goto fpsimd_only;
    }

    vq = sve_vq_from_vl(sve.vl);

    if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
        return -EINVAL;

    /*
     * Careful: we are about __copy_from_user() directly into
     * thread.sve_state with preemption enabled, so protection is
     * needed to prevent a racing context switch from writing stale
     * registers back over the new data.
     */

    fpsimd_flush_task_state(current);
    barrier();
    /* From now, fpsimd_thread_switch() won't clear TIF_FOREIGN_FPSTATE */

    set_thread_flag(TIF_FOREIGN_FPSTATE);
    barrier();
    /* From now, fpsimd_thread_switch() won't touch thread.sve_state */

    sve_alloc(current);
    err = __copy_from_user(current->thread.sve_state,
                   (char __user const *)user->sve +
                    SVE_SIG_REGS_OFFSET,
                   SVE_SIG_REGS_SIZE(vq));
    if (err)
        return -EFAULT;

    set_thread_flag(TIF_SVE);

fpsimd_only:
    /* copy the FP and status/control registers */
    /* restore_sigframe() already checked that user->fpsimd != NULL. */
    err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
                   sizeof(fpsimd.vregs));
    __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
    __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);

    /* load the hardware registers from the fpsimd_state structure */
    if (!err)
        fpsimd_update_current_state(&fpsimd);

    return err ? -EFAULT : 0;
}

#else /* ! CONFIG_ARM64_SVE */

/* Turn any non-optimised out attempts to use these into a link error: */
extern int preserve_sve_context(void __user *ctx);
extern int restore_sve_fpsimd_context(struct user_ctxs *user);

#endif /* ! CONFIG_ARM64_SVE */


static int parse_user_sigframe(struct user_ctxs *user,
                   struct rt_sigframe __user *sf)
{
    struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
    struct _aarch64_ctx __user *head;
    char __user *base = (char __user *)&sc->__reserved;
    size_t offset = 0;
    size_t limit = sizeof(sc->__reserved);
    bool have_extra_context = false;
    char const __user *const sfp = (char const __user *)sf;

    user->fpsimd = NULL;
    user->sve = NULL;

    if (!IS_ALIGNED((unsigned long)base, 16))
        goto invalid;

    while (1) {
        int err = 0;
        u32 magic, size;
        char const __user *userp;
        struct extra_context const __user *extra;
        u64 extra_datap;
        u32 extra_size;
        struct _aarch64_ctx const __user *end;
        u32 end_magic, end_size;

        if (limit - offset < sizeof(*head))
            goto invalid;

        if (!IS_ALIGNED(offset, 16))
            goto invalid;

        head = (struct _aarch64_ctx __user *)(base + offset);
        __get_user_error(magic, &head->magic, err);
        __get_user_error(size, &head->size, err);
        if (err)
            return err;

        if (limit - offset < size)
            goto invalid;

        switch (magic) {
        case 0:
            if (size)
                goto invalid;

            goto done;

        case FPSIMD_MAGIC:
            if (user->fpsimd)
                goto invalid;

            if (size < sizeof(*user->fpsimd))
                goto invalid;

            user->fpsimd = (struct fpsimd_context __user *)head;
            break;

        case ESR_MAGIC:
            /* ignore */
            break;

        case SVE_MAGIC:
            if (!system_supports_sve())
                goto invalid;

            if (user->sve)
                goto invalid;

            if (size < sizeof(*user->sve))
                goto invalid;

            user->sve = (struct sve_context __user *)head;
            break;

        case EXTRA_MAGIC:
            if (have_extra_context)
                goto invalid;

            if (size < sizeof(*extra))
                goto invalid;

            userp = (char const __user *)head;

            extra = (struct extra_context const __user *)userp;
            userp += size;

            __get_user_error(extra_datap, &extra->datap, err);
            __get_user_error(extra_size, &extra->size, err);
            if (err)
                return err;

            /* Check for the dummy terminator in __reserved[]: */

            if (limit - offset - size < TERMINATOR_SIZE)
                goto invalid;

            end = (struct _aarch64_ctx const __user *)userp;
            userp += TERMINATOR_SIZE;

            __get_user_error(end_magic, &end->magic, err);
            __get_user_error(end_size, &end->size, err);
            if (err)
                return err;

            if (end_magic || end_size)
                goto invalid;

            /* Prevent looping/repeated parsing of extra_context */
            have_extra_context = true;

            base = (void __user *)extra_datap;
            if (!IS_ALIGNED((unsigned long)base, 16))
                goto invalid;

            if (!IS_ALIGNED(extra_size, 16))
                goto invalid;

            if (base != userp)
                goto invalid;

            /* Reject "unreasonably large" frames: */
            if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
                goto invalid;

            /*
             * Ignore trailing terminator in __reserved[]
             * and start parsing extra data:
             */
            offset = 0;
            limit = extra_size;

            if (!access_ok(base, limit))
                goto invalid;

            continue;

        default:
            goto invalid;
        }

        if (size < sizeof(*head))
            goto invalid;

        if (limit - offset < size)
            goto invalid;

        offset += size;
    }

done:
    return 0;

invalid:
    return -EINVAL;
}

static int restore_sigframe(struct pt_regs *regs,
                struct rt_sigframe __user *sf)
{
    sigset_t set;
    int i, err;
    struct user_ctxs user;

    err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
    if (err == 0)
        set_current_blocked(&set);

    for (i = 0; i < 31; i++)
        __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
                 err);
    __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
    __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
    __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);

    /*
     * Avoid sys_rt_sigreturn() restarting.
     */
    forget_syscall(regs);

    err |= !valid_user_regs(&regs->user_regs, current);
    if (err == 0)
        err = parse_user_sigframe(&user, sf);

    if (err == 0) {
        if (!user.fpsimd)
            return -EINVAL;

        if (user.sve) {
            if (!system_supports_sve())
                return -EINVAL;

            err = restore_sve_fpsimd_context(&user);
        } else {
            err = restore_fpsimd_context(user.fpsimd);
        }
    }

    return err;
}

SYSCALL_DEFINE0(rt_sigreturn)
{
    struct pt_regs *regs = current_pt_regs();
    struct rt_sigframe __user *frame;

    /* Always make any pending restarted system calls return -EINTR */
    current->restart_block.fn = do_no_restart_syscall;

    /*
     * Since we stacked the signal on a 128-bit boundary, then 'sp' should
     * be word aligned here.
     */
    if (regs->sp & 15)
        goto badframe;

    frame = (struct rt_sigframe __user *)regs->sp;

    if (!access_ok(frame, sizeof (*frame)))
        goto badframe;

    if (restore_sigframe(regs, frame))
        goto badframe;

    if (restore_altstack(&frame->uc.uc_stack))
        goto badframe;

    return regs->regs[0];

badframe:
    arm64_notify_segfault(regs->sp);
    return 0;
}

/*
 * Determine the layout of optional records in the signal frame
 *
 * add_all: if true, lays out the biggest possible signal frame for
 *	this task; otherwise, generates a layout for the current state
 *	of the task.
 */
static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
                 bool add_all)
{
    int err;

    err = sigframe_alloc(user, &user->fpsimd_offset,
                 sizeof(struct fpsimd_context));
    if (err)
        return err;

    /* fault information, if valid */
    if (add_all || current->thread.fault_code) {
        err = sigframe_alloc(user, &user->esr_offset,
                     sizeof(struct esr_context));
        if (err)
            return err;
    }

    if (system_supports_sve()) {
        unsigned int vq = 0;

        if (add_all || test_thread_flag(TIF_SVE)) {
            int vl = sve_max_vl;

            if (!add_all)
                vl = current->thread.sve_vl;

            vq = sve_vq_from_vl(vl);
        }

        err = sigframe_alloc(user, &user->sve_offset,
                     SVE_SIG_CONTEXT_SIZE(vq));
        if (err)
            return err;
    }

    return sigframe_alloc_end(user);
}

static int setup_sigframe(struct rt_sigframe_user_layout *user,
              struct pt_regs *regs, sigset_t *set)
{
    int i, err = 0;
    struct rt_sigframe __user *sf = user->sigframe;

    /* set up the stack frame for unwinding */
    __put_user_error(regs->regs[29], &user->next_frame->fp, err);
    __put_user_error(regs->regs[30], &user->next_frame->lr, err);

    for (i = 0; i < 31; i++)
        __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
                 err);
    __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
    __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
    __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);

    __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);

    err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));

    if (err == 0) {
        struct fpsimd_context __user *fpsimd_ctx =
            apply_user_offset(user, user->fpsimd_offset);
        err |= preserve_fpsimd_context(fpsimd_ctx);
    }

    /* fault information, if valid */
    if (err == 0 && user->esr_offset) {
        struct esr_context __user *esr_ctx =
            apply_user_offset(user, user->esr_offset);

        __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
        __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
        __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
    }

    /* Scalable Vector Extension state, if present */
    if (system_supports_sve() && err == 0 && user->sve_offset) {
        struct sve_context __user *sve_ctx =
            apply_user_offset(user, user->sve_offset);
        err |= preserve_sve_context(sve_ctx);
    }

    if (err == 0 && user->extra_offset) {
        char __user *sfp = (char __user *)user->sigframe;
        char __user *userp =
            apply_user_offset(user, user->extra_offset);

        struct extra_context __user *extra;
        struct _aarch64_ctx __user *end;
        u64 extra_datap;
        u32 extra_size;

        extra = (struct extra_context __user *)userp;
        userp += EXTRA_CONTEXT_SIZE;

        end = (struct _aarch64_ctx __user *)userp;
        userp += TERMINATOR_SIZE;

        /*
         * extra_datap is just written to the signal frame.
         * The value gets cast back to a void __user *
         * during sigreturn.
         */
        extra_datap = (u64)userp;
        extra_size = sfp + round_up(user->size, 16) - userp;

        __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
        __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
        __put_user_error(extra_datap, &extra->datap, err);
        __put_user_error(extra_size, &extra->size, err);

        /* Add the terminator */
        __put_user_error(0, &end->magic, err);
        __put_user_error(0, &end->size, err);
    }

    /* set the "end" magic */
    if (err == 0) {
        struct _aarch64_ctx __user *end =
            apply_user_offset(user, user->end_offset);

        __put_user_error(0, &end->magic, err);
        __put_user_error(0, &end->size, err);
    }

    return err;
}

static int get_sigframe(struct rt_sigframe_user_layout *user,
             struct ksignal *ksig, struct pt_regs *regs)
{
    unsigned long sp, sp_top;
    int err;

    init_user_layout(user);
    err = setup_sigframe_layout(user, false);
    if (err)
        return err;

    sp = sp_top = sigsp(regs->sp, ksig);

    sp = round_down(sp - sizeof(struct frame_record), 16);
    user->next_frame = (struct frame_record __user *)sp;

    sp = round_down(sp, 16) - sigframe_size(user);
    user->sigframe = (struct rt_sigframe __user *)sp;

    /*
     * Check that we can actually write to the signal frame.
     */
    if (!access_ok(user->sigframe, sp_top - sp))
        return -EFAULT;

    return 0;
}

static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
             struct rt_sigframe_user_layout *user, int usig)
{
    regs->regs[0] = usig;
    regs->sp = (unsigned long)user->sigframe;
    regs->regs[29] = (unsigned long)&user->next_frame->fp;
    regs->pc = (unsigned long)ka->sa.sa_handler;

    regs->regs[30] = (unsigned long)ka->sa.sa_restorer;
}

static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
              struct pt_regs *regs)
{
    struct rt_sigframe_user_layout user;
    struct rt_sigframe __user *frame;
    int err = 0;

    fpsimd_signal_preserve_current_state();

    if (get_sigframe(&user, ksig, regs))
        return 1;

    frame = user.sigframe;

    __put_user_error(0, &frame->uc.uc_flags, err);
    __put_user_error(NULL, &frame->uc.uc_link, err);

    err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
    err |= setup_sigframe(&user, regs, set);
    if (err == 0) {
        setup_return(regs, &ksig->ka, &user, usig);
        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
            err |= copy_siginfo_to_user(&frame->info, &ksig->info);
            regs->regs[1] = (unsigned long)&frame->info;
            regs->regs[2] = (unsigned long)&frame->uc;
        }
    }

    return err;
}

static void setup_restart_syscall(struct pt_regs *regs)
{
    regs->regs[8] = __NR_seminix_restart_syscall;
}

/*
 * OK, we're invoking a handler
 */
static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
    sigset_t *oldset = sigmask_to_save();
    int usig = ksig->sig;
    int ret;

    /*
     * Set up the stack frame
     */
    ret = setup_rt_frame(usig, ksig, oldset, regs);

    /*
     * Check that the resulting registers are actually sane.
     */
    ret |= !valid_user_regs(&regs->user_regs, current);

    signal_setup_done(ret, ksig, 0);
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 *
 * Note that we go through the signals twice: once to check the signals that
 * the kernel can handle, and then we build all the user-level signal handling
 * stack-frames in one go after that.
 */
static void do_signal(struct pt_regs *regs)
{
    unsigned long continue_addr = 0, restart_addr = 0;
    int retval = 0;
    struct ksignal ksig;
    bool syscall = in_syscall(regs);

    /*
     * If we were from a system call, check for system call restarting...
     */
    if (syscall) {
        continue_addr = regs->pc;
        restart_addr = continue_addr - 4;
        retval = regs->regs[0];

        /*
         * Avoid additional syscall restarting via ret_to_user.
         */
        forget_syscall(regs);

        /*
         * Prepare for system call restart. We do this here so that a
         * debugger will see the already changed PC.
         */
        switch (retval) {
        case -ERESTARTNOHAND:
        case -ERESTARTSYS:
        case -ERESTARTNOINTR:
        case -ERESTART_RESTARTBLOCK:
            regs->regs[0] = regs->orig_x0;
            regs->pc = restart_addr;
            break;
        }
    }

    /*
     * Get the signal to deliver. When running under ptrace, at this point
     * the debugger may change all of our registers.
     */
    if (get_signal(&ksig)) {
        /*
         * Depending on the signal settings, we may need to revert the
         * decision to restart the system call, but skip this if a
         * debugger has chosen to restart at a different PC.
         */
        if (regs->pc == restart_addr &&
            (retval == -ERESTARTNOHAND ||
             retval == -ERESTART_RESTARTBLOCK ||
             (retval == -ERESTARTSYS &&
              !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
            regs->regs[0] = -EINTR;
            regs->pc = continue_addr;
        }

        handle_signal(&ksig, regs);
        return;
    }

    /*
     * Handle restarting a different system call. As above, if a debugger
     * has chosen to restart at a different PC, ignore the restart.
     */
    if (syscall && regs->pc == restart_addr) {
        if (retval == -ERESTART_RESTARTBLOCK)
            setup_restart_syscall(regs);
    }

    restore_saved_sigmask();
}

asmlinkage void do_notify_resume(struct pt_regs *regs,
                 unsigned long thread_flags)
{
    do {
        /* Check valid user FS if needed */
        addr_limit_user_check();

        if (thread_flags & _TIF_WORK_RESCHED) {
            /* Unmask Debug and SError for the next task */
            local_daif_restore(DAIF_PROCCTX_NOIRQ);

            if (thread_flags & _TIF_NEED_STOPED) {
                set_current_state(TASK_STOPED);
                clear_thread_flag(TIF_NEED_STOPED);
            }

            schedule();
        } else {
            local_daif_restore(DAIF_PROCCTX);

            if (thread_flags & _TIF_SIGPENDING)
                do_signal(regs);

            if (thread_flags & _TIF_FOREIGN_FPSTATE)
                fpsimd_restore_current_state();
        }

        local_daif_mask();
        thread_flags = READ_ONCE(current_thread_info()->flags);
    } while (thread_flags & _TIF_WORK_MASK);
}

unsigned long __ro_after_init signal_minsigstksz;

/*
 * Determine the stack space required for guaranteed signal devliery.
 * This function is used to populate AT_MINSIGSTKSZ at process startup.
 * cpufeatures setup is assumed to be complete.
 */
void __init minsigstksz_setup(void)
{
    struct rt_sigframe_user_layout user;

    init_user_layout(&user);

    /*
     * If this fails, SIGFRAME_MAXSZ needs to be enlarged.  It won't
     * be big enough, but it's our best guess:
     */
    if (WARN_ON(setup_sigframe_layout(&user, true)))
        return;

    signal_minsigstksz = sigframe_size(&user) +
        round_up(sizeof(struct frame_record), 16) +
        16; /* max alignment padding */
}
